This rings so true to me. In fifth grade after being given an IQ test, I took Algebra I early, only to retake it when I moved to junior high the next year. Then I had to retake trig because I did no homework, but aced the tests. Luckily the teacher recognized my ability and allowed me to take pre-calc while I retook trig.

By the time I was in undergrad I had no motivation to study. I'd skip classes and cram the night before for any class that was memorization based. I didn't even buy the books, just went to the library and checked the book out for a couple hours.

Fast forward a bit and I ended up dropping some classes because I was paying so little attention, I didn't even know when the tests were supposed to be. Came in one day and the prof said, "You missed the test last week, I presume you want to retake it?"

That said, I've done well enough having gone back later in life to get a PhD, but I do wonder sometimes if I would have accomplished more if I was forced to push the boundaries of my ability, thus leading me to develop a work ethic earlier on.